When HERDA Strikes

A diagnosis of hereditary equine regional dermal asthenia (HERDA), or hyperelastosis cutis (HC), is frequently a grim one for horse owners. The hereditary skin disease that affects some stock horse breeds can result in isolation for turnout and skin lesions for the afflicted horse, and mounting veterinary expenses and heartache for the owner. But one horse-and-owner pair is proving that it's possible to live with HERDA and to have a good time in spite of it all.

Robin Davison bought her registered Paint mare, Quality Sensation ("Penelope") to replace the mare she'd unexpectedly had to put down following surgical complications. Penelope was to be Davison's show mount, her "everything" horse, and she had high hopes for the talented youngster. Then, tragedy struck.

Robin Davison and Penelope now train and compete in ground-working classes like showmanship to keep the mare comfortable.

"We were starting her under saddle in February, and she developed saddle sores that didn't heal after several weeks' layoff," said Davison. "My veterinarian then sent a hair sample off to the UC-Davis (University of California, Davis) lab for analysis."

When the news came back via e-mail, Davison said, "I literally couldn't breathe when I first got the diagnosis."

While HERDA is not common, it can be serious; afflicted horses have poorly healing, fragile skin that's prone to fluid-filled lesions (seromas), tearing, and scarring, and many are unrideable. The gene is characterized as being autosomal recessive, which means that both parents must pass it on for their offspring to be affected.

According to Nena Winand, DVM, PhD, of Cornell University, HERDA can happen to anyone. "Robin did everything right, and the horse had a prepurchase exam, but look at what happened," she says. "It's important that people be aware of this disease and its consequences, which include direct contact injuries from just about anything in the average horse's environment, including tack."

Winand, who has studied the genetics, pathophysiology, and clinical management of HERDA horses, says it's crucial to not neglect training even if the horse is turned out to pasture.

"Most owners want to do the right thing, but they forget that a horse needs enough training and handling in order to allow for routine farrier and veterinary care, as well as wound management," she advised.

As for Penelope's safety, Davison has done everything she can, but said that she's also made a conscious decision to let her just be a horse. "Penelope's living in a shaded outdoor run made of metal panel fencing, which is smooth and won't damage her skin, and there's nothing in her run or shed to injure herself on," says Davison. The mare's constant companion is a retired petting zoo goat named Ned, but she also gets occasional, supervised turnout with an equine friend.

Winand recommended that owners become out-of-the-box thinkers about what a horse's job can be and that's just what Davison is doing; the pair has participated in several local shows and clinics, with plans to do more.

"She'll most likely die from this disease, but in the meantime we're learning what's possible," says Davison. "I figure I'll get really good at groundwork, and we'll find fun things to do together."